Fireproofing composition for cellulosic materials

ABSTRACT

Cellulosic fibers or fabrics of a bleached or pastel shaded coloring when impregnated with additives for imparting unique characteristics, such as fire retardancy, and subjected to temperatures such as are encountered in drying and curing operations, generally exhibit definite and permanent discoloration. Such discoloration can be avoided or minimized if the treated cellulosic fibrous substrates have hydrazine or derivatives thereof incorporated into the additive prior to a heat treatment operation. For example, if an aqueous composition being applied to rayon or other cellulosic material consists essentially of an inorganic nitrogen-phosphorus polymeric resinous flame-proofing reaction product and hydrazine, the impregnated fabric, when dried and subject to a heat curing operation, shows little or no discoloration.

[ 41 FIREPROOFING COMPOSITION FOR CELLULOSIC MATERIALS Jay C. Chapin, Marblehead, Mass.

[73] Assignee: Ventron Instruments Corp.,

Scientific Chemicals Division, Beverly, Mass.

22 Filed: Jan. 11,1971

21 Appl. N.o.: 105,629

[75] Inventor:

[52] US. Cl ..117/137, 117/138, 117/143 A, 252/8.l [51] Int. Cl. C09k 3/28, D06m 13/26 [58] Field of Search 117/136, 137, 143 A, 117/138; 252/81; 106/15 Fl [56] References Cited UNITED STATES PATENTS 3,101,279 8/1963 Wagner et al. 117/137 2,809,941 10/1957 Reeves et al..... 1 17/136 X 3,565,679 2/1971 Strother 117/136 2,964,377 12/1960 Costello 1l7/138 X 3,029,283 4/1962 Steinhauer 117/136 X 2,600,455 6/1952 Wilson et al..... 106/15 X 2,661,264 12/1953 Malowan 23/357 2,996,357 8/1961 Koster et al. 23/357 Aug. 28, 1973 3,032,440 5/1962 lannazzi 117/138 3,510,453 5/1970 Geiser I. 1 17/136 X 3,310,420 3/1967 Wagner 117/136 X [57] ABSTRACT Cellulosic fibers or fabrics of a bleached or pastel shaded coloring when impregnated with additives for imparting unique characteristics, such as fire retardancy, and subjected to temperatures such as are encountered in drying and curing operations, generally exhibit definite and permanent discoloration. Such discoloration can be avoided or minimized if the treated cellulosic fibrous substrates have hydrazine or derivatives thereof incorporated into the additive prior to a heat treatment operation. For example, if an aqueous composition being applied to rayon or other cellulosic material consists essentially of an inorganic nitrogenphosphorus polymeric resinous flame-proofing reaction product and hydrazine, the impregnated fabric, when dried and subject to a heat curing operation, shows little or no discoloration.

3 Claims, No Drawings FIREPROOFING COMPOSITION FOR CELLULOSIC MATERIALS This invention relates to a method of treating cellulosic materials, which will inhibit discoloration of white or light colored cellulosic fibrous substrates upon being heat treated at temperatures of the order of 100C. or higher. More particularly, it relates to cellulosic fabrics, i.e., fibrous substrates such as rayon, having sorbed compositions for imparting unique characteristics, adhered thereto which contain hydrazine or derivatives thereof to render the treated cellulosic materials resistant to discoloration at the time of subjection to heat treatments. Still more particularly, it relates to compositions which will render cellulosic materials fire resistant and can be cured to an adherent coating by heat treatment without causing discoloration or fiber tenderizing of the treated cellulosic material, comprising hydrazine, hydrazine salts, or certain hydrazine derivatives and a resinous inorganic polymeric nitrogenphosphorus reaction product.

Briefly, the method of providing resistance to discoloration of cellulosic substrates havingcompositions deposited thereon from aqueous mediums, for example, compositions to provide fire resistance properties, during heat treatments at temperatures of 100C. or higher, comprises incorporating into the deposited composition, simultaneously with or subsequent to deposition a compound selected from the group consisting of hydrazine, hydrazine salts and hydrazine derivatives in which the hydrogens of the H NNH base are only partly substituted.

The compositions of this invention used to incorporate the water soluble compound selected from the group consisting of hydrazine, hydrazine salts and hydrazine derivatives in which the hydrogens of the lbN-NH base are only partially substituted, may consist solely of water and hydrazine compound for application after the substrate has the characterizing material deposited thereon or may comprise aqueous solutions of the characterizing material, such as a fire retardant resinous material, characterizing resinous material plus curing agents, etc., having the hydrazine compound dissolved therein.

Cellulosic textiles commonly have agents applied thereto which will impart specific characteristics. When such treated cellulosic textiles are light in color, i.e., are of the pastel shade or bleached type, and the additive agent must be subjected to heat treatment in excess of 100C. to'convert the additive to a form which will be permanently attached to the fabric so that the imparted property is durable, discoloration may occur during the heat treatment.

For example, in producing flame retardant textiles when the light colored textile is impregnated with a flame retardant agent such as an inorganic nitrogenphosphorus agent by deposition thereon from an aqueous medium, the impregnated cellulosic substrate must be subjected to heat treatment to induce reaction with the cellulose to produce a water-insoluble form or to render the flame retardant agent itself water-insoluble so that the flame retardancy will not be lost in laundering. Such heat treatment can effect discoloration of light colored cellulosic fabrics. Generally, more discoloration is noted the higher the temperature.

Discoloration, such as yellowing or blacking of white textiles and darkening of paste] colored textiles, is not eliminated by incorporation of well known buffering agents such as alkali metal acetates, phthalates, etc., or anti-oxidants such as phenyl naphthylamine or reducing agents such as sodium hydrosulfite, etc., into the residuum compositions.

Now it has been discovered that light colored cellulosic fibers and/or fabrics, i.e., fibrous substrates, such as cotton and rayon or blends of such cellulosic fibers, for example with synthetic resin fibers, can be protected against such deleterious actions as discoloration, when the impregnated cellulosic substrate is to be subjected to heat treatments at temperatures of the order of C. to 200C. by incorporating into the sorbed impregnant a water soluble compound selected from the group consisting of hydrazine, hydrazine salts and derivatives thereof which have only partial substitution of the hydrogens of the ll N-Nll base.

In accordance with this invention, the water soluble hydrazine compound is incorporated in amounts which will provide the impregnated fabric on a dry weight basis, with from 0.05 to 0.5 percent by weight of the fabric, based upon the hydrazine equivalent of the compound.

A composition, illustrativeof a preferred specific embodiment of the invention, is one applicable from aqueous medium and adapted when deposited upon cellulosic fibrous substrates to render said substrates flame resistant and provide said substrates with resistance to discoloration produced by the heat treatment required to convert the resinous component to a water-insoluble form. The composition comprises water, hydrazine compound and a nitrogen-phosphorous containing flame-proofing agent of the resinous type. The flameproofing agent constituting from 10 to 50 percent by weight of the total composition.

Such a water-soluble nitrogen-phosphorus material may be produced by slurrying the product of reaction of anhydrous ammonia and a phosphoric compound such as phosphorus pentoxide or phosphorus oxychloride in a water-insoluble carrier liquid, such as trichlorethylene, mixing aqueous ammonium hydroxide with said slurry while maintaining a temperature up to 40C. until, upon standing without agitation, a homogeneous, lower liquid reaction product phase separates from a top floating carrier liquid phase and separating the phases to recover the homogeneous reaction product liquid which contains l5 to 30 percent by weight of water. Such a reaction product liquid is a complex mixture of polymeric materials which when applied to cellulosic materials imparts flameproofing and may be cured at temperatures of the order of C. (302F.) to C. (374F.) to a water-insoluble finish.

Compounds having a l-l,N-NH base, useful in the preparation of textile treating compositions of this invention, are hydrazine itself, hydrazine hydrate, inorganic salts of hydrazine such as hydrazine monoand dihydro-chloride, hydrazine sulfate, dihydrazine sulfate, organic derivatives of hydrazine such as pyrazole, semicarbazides, aminoguanidines and substituted hydrazines, the hydrogens of which are only partially replaced by, for example, alkyl substituents totaling less than 10 carbon atoms, etc.

Hydrazine or hydrazine hydrate is the most effective member of this group when compared on the basis of depositing 0.05 to 0.5 grams of hydrazine per 100 grams of cellulose fabric. The most effective of the other members of the group when used to deposit equivalent amounts of hydrazine is hydrazine sulfate. The effectiveness of hydrazine sulfate, like hydrazine hydrate, decreases approximately proportional to the reduction in quantity used. Other compounds such as hydrazine dihydrochloride, semicarbazide and pyrazole also have a high degree of effectiveness.

The effectiveness of hydrazine compounds in the compositions used to impregnate cellulosic substrate is attributable at least in part to the stability of the hydrazine compounds and the salts thereof at the temperatures required for the drying and curing operations. Use of hydrazine compounds in compositions containing components which will react with the hydrazine compounds before drying and curing temperatures are attained, naturally is to be avoided. A typical material which will react with the hydrazine and thereby reduce its effectiveness in preventing discoloration is a material containing oxo groups such as aldehydes, aldehyde precursors and ketones, for example, ureaformaldehyde resin.

An aqueous composition for treating cellulosic substrates may be prepared by heating approximately 300 pounds of water to a temperature in the range between about 65C. (149F.) and 85C. (176F.). Sufficient nitrogen phosphorus-containing compounds such as the reaction product described previously, is added to the hot water to produce a solution of roughly 20 to 30 percent solids by weight. A compound having a l-l N-NH base, for simplicity of explanation purposes, hydrazine, is added to the solution of resinous agent, in quantities providing between about 0.1 and 1.5 by weight of the solution or the equivalent thereof based upon the hydrazine equivalent weight of the added agent. The concentration of the treating bath may be varied when treating the fabric to be impregnated, as a means of partially controlling the amount of add-on in the fabric.

By hydrazine equivalent weight we mean that, if 1.0 pound of hydrazine (molecular weight of 32.05) is to be used, the equivalent amount of hydrazine dihydrochloride (molecular weight of 104.98) is 3.27 pounds, i.e., a quantity which introduces the same quantity of H N-Nl-l into the treating solution.

Examples of nitrogen-phosphorus containing resinous products having fire retardant properties, as illustrated in US. Pat. No. 3,029,283, are products of reaction of anhydrous ammonia-phosphorus pentoxide reaction products with ammonium hydroxide, products of reaction of anhydrous ammonia-phosphorus pentoxide reaction product with ethylenediamine, and the like.

When a fabric, such as cotton duck, rayon fabric, etc., is passed through a fire retardant treating solution and then between squeeze rolls, the adhesive solution adhering to the fabric generally constitutes an add-on of approximately 60 to 70 wet weight based upon the original dry weight of the fabric, and upon drying shows a residuum, i.e., a dry add-on, of about to percent by weight, i.e., a weight increase percentage level based upon the original dry weight of the fabric. Such a treated fabric is cured after drying at a temperature of, for example, 163C. (325F.) for three minutes.

Compositions for flameproofing fabrics such as that described above, may also contain buffering agents such as dicyandiamide in amounts constituting about 1 to 5 percent of the total compositions. The presence of such organic agents permits use of higher curing temperatures for the resinous component without exces' sive fabric tenderization during the heating step. The data in Table 1 indicates that dicyandiamide buffer is not a substitute for hydrazine in the instant composition for treating cellulosic materials but serves an entirely different purpose.

A treated cotton duck is tested for flame resistance by the 1951 Fed. Specifications Method No. 5902, CCC-T-l91 (b). Briefly, the test involves 12 second exposure to a Bunsen burner flame to determine if the heated material is selfextinguishing.

The invention is further illustrated by the following examples which are given by way ofillustration of preparation of the flameproofing agent used in the tests and various compositions tested, and without any intention that the invention be limited thereto.

EXAMPLE I An aqueous coating composition is prepared from the aqueous solution of a N-P reaction product resulting from reaction of 500 parts by weight of a powdered product produced by reaction of anhydrous ammonia with a phosphoric acid anhydride selected from the group consisting of phosphorus pentoxide and phosphorus oxychloride (Victamide produced by Stauffer Chemical Company) which is dispersed in 250 parts by weight of 27 percent ammonium hydroxide at a temperature of 35C. (800 parts by weight of trichlorethylene).

450 pounds of the N-P reaction product, recovered as a syrupy solution containing approximately 35 percent by weight of water, is added to 550 pounds of water heated to a temperature of about C. and the mixture agitated until there is complete solution.

EXAMPLE II To approximately 488 pounds of the solution prepared by dissolving the syrupy solution produced as described in Example I, is added 12 pounds of dicyandiamide. The aqueous mixture is agitated until the solution is homogeneous.

EXAMPLE Ill To approximately 483 pounds of the solution prepared by dissolving the syrupy solution produced as described in Example l are added 3.75 pounds of percent hydrazine hydrate and 12 pounds of dicyandiamide. The aqueous mixture is agitated until the solution is homogeneous. The aqueous mixture contains approximately 0.48 percent by weight of N,H,. A corresponding composition containing approximately 0.64 percent by weight of N l-l was prepared by increasing the amount of hydrazine hydrate to 5 pounds.

EXAMPLE IV To approximately 478 pounds of the solution prepared by dissolving the syrupy solution produced as de scribed in Example 1 are added 12 pounds of dicyandiamide and 15.75 pounds of hydrazine dihydrochloride. The aqueous mixture is agitated until the solution is homogeneous. The aqueous mixture contains approximately 0.48 percent by weight of N 11 A corresponding composition containing approximately 0.64 percent by weight of N 11, was prepared by increasing the amount of hydrazine dihydrochloride to 21 pounds.

EXAMPLE V To approximately 475 pounds of the solution prepared by dissolving the syrupy solution produced as described in Example I are added 12 pounds of dicyandiamide and 19.5 pounds of hydrazine sulfate. The aqueous mixture is agitated until the solution is homogeneous. The aqueous mixture contains 0.48 percent by weight of N IL. A corresponding composition containing 0.64 percent by weight was prepared by increasing the amount of hydrazine sulfate to 26 pounds.

EXAMPLE IV To approximately 480 pounds of the solution prepared by dissolving the syrupy solution produced as described in Example I are added 12 pounds of dicyandiamide and 1 1.25 pounds of semicarbazide. The aqueous mixture is agitated until the solution is homogeneous. The aqueous mixture contains an equivalent of 0.48 percent by weight of N IL. A corresponding composition containing 0.64 percent by weight of N I-I was prepared by increasing the amount of semicarbazide to pounds.

EXAMPLE VII Separate portions of a cotton/rayon fabric, i.e., cellucompositions of Examples II to VI, identified by the letters B through F and the material identified by G which is the composition of Example I1 containing 5.85 pounds and 7.8 pounds of ethylene diamine to incorporate the equivalent amounts of PEN-NR of 0.48 percent and 0.64 percent, respectively. The two samples each of materials A, B and G, the treatment compositions of which contained no hydrazine agent were heat treated for drying and curing at 150C. for 7 minutes and at 170C. for 4 minutes. The samples of fabric identified as materials C through F, i.e., fabric treated with a composition containing 0.48 percent H N-NH based upon the amount of hydrazine compound incorporated, were also heat treatedfor drying and curing at 150C. for 7 minutes and at 170C. for 4 minutes. The samples of fabric identified as materials C through E, i.e., fabric treated with the same basic composition but containing 0.64 percent H NNH based upon the amount of hydrazine compound incorporated were likewise heat treated for drying and curing at 150C. for 7 minutes and at 170C. for 4 minutes.

The data shows a definite discoloration of the sample TABLE I Relative whiteness of treated cotton/rayon fabric 0 NIHI 0.48% NzHi 0.64% Nzlli 300 F. 340 F. 300 F. 340 F. 300 F. 340 F. Material (150 C.) (170 C.) (150 C.) (170 C.) (150 C.) (170 C.)

A Water 57. 5 50 B Product of Example II. 18 0.3 C. Product of Example III 39. 5 24 44. 5 19 D 37. 5 14 33 21 E 38- 23.5 36.5 25.5 F 41. 5 19 45 18. 5 5. 5 3 7. 5 5. 5

G Ethylene diamine losic material, were provided with a fire retardant finish of each of the compositions of Examples II through VI, as follows: i

Strips cut from 8.5 oz./yard white, bleached fabric consisting of percent by weight of cotton and 70 percent by weight of rayon were passed through one each of the hot impregnating compositions. After passage between squeeze rolls, the fabric strips impregnated with compositions containing resinous material prepared as described in the Examples had a wet addon of about 70 percent by weight. The weight of coating agent adhering to a fabric referred to as add-on is expressed as a proportion, i.e., percentage, of the total weight of fabric plus coating composition. After drying at 1 10C., the fabric strips show a dry add-on of 15 percent by weight. The impregnated fabric was cured at a temperature of 150C. (302F.) to 170C. (338F.). Typical times for drying and curing in one operation is 7 minutes at 150C. and 4% minutes at 170C., followed by rinsing and drying-for 2 minutes at l 10C.

Difference in color were determined by reflectance measurements using a I-Iunterfab Model D40 reflectometer at the standard blue and green wavelengths. The greater the relative whiteness number, the less the discoloration. The control sample of untreated fabric showed a relative whiteness of and a fabric with no treating composition which has been wetted and heat treated showed a reflectometer reading of the order of 57.5 and 50 at the temperatures of 300F. and 340F., respectively.

The following Table I shows the results of reflectance measurements on white 30 percent cotton/70 percent rayon fabric treated with each of the flame retardant of fabric impregnated with the aqueous solution of the resinous product of Example II and when a basic material such as ethylene diamine is added to the aqueous treating composition from .which the fire retardant is deposited on the fabric. The compositions of this invention described in Examples III through VI show practically no change in color due to curing at a temperature of 300F. (149C.) but at a cure temperature of 340F. (171C.) hydrazine sulfate and hydrazine hydrate are the most effective agents at either of the hydrazine concentrations indicated.

I claim:

I. A durably fire resistant cellulosic textile fabric comprising a cellulosic textile fabric impregnated with the combination of (a) a watersoluble compound effective for inhibiting discoloration of said cellulosic fabric under curing conditions selected from the group consisting of hydrazine, hydrazine salts and derivatives thereof which have only partial substitution of the hydrogens of the [LN-NH, base and (b) a water-soluble inorganic resin which is the product of reaction of dilute aqueous ammonium hydroxide with the reaction product of anhydrous ammonia and a phosphorus compound selected from the group consisting of phosphorus pentoxide and phosphorus oxychloride, said resin being in polymeric fonn non-reactable with said compound and heat curable to a water-insoluble finish in the absence of components that will react with said water-soluble compound before drying and curing termperatures are attained, said impregnated fabric to which said combination was added in aqueous solution form being dried and said resin heat cured in situ to a waterinsoluble condition upon said textile fabric.

2. The article of claim 1 in which said fabric comprises cotton fiber.

3. A fire retardant cellulosic textile fabric consisting essentially of cellulosic fibers impregnated with an aqueous composition consisting of an aqueous medium having dissolved therein 0.1 to 1.5 percent by weight of the total composition of a water-soluble compound effective for inhibiting discoloration of said cellulosic fabric under curing conditions and selected from the group consisting of hydrazine, hydrazine salts and derivatives thereof which have only partial substitution of the hydrogens of the l-l,l\l-NH base and having between l and 50 percent by weight of the total composition of a water-soluble inorganic resinous polymeric material produced by reaction of dilute ammonium hydroxide with the reaction product of anhydrous ammonia and a phosphorus compound selected from the group consisting of phosphorus pentoxide and phosphorus oxychloride, said resin being in polymeric form non-reactable with said water-soluble compound and heat curable to a water-insoluble finish in the absence of components which will react with said water-soluble compound before drying and curing temperatures are attained, said resinous component being present as an impregnant in an amount in the range between 15 and 20 percent based upon the dry weight of said fabric and said compound being present as an impregnant in an amount in the range between about 0.05 and 0.5 percent based upon the dry weight of said fabric. 

2. The article of claim 1 in which said fabric comprises cotton fiber.
 3. A fire retardant cellulosic textile fabric consisting essentially of cellulosic fibers impregnated with an aqueous composition consisting of an aqueous medium having dissolved therein 0.1 to 1.5 percent by weight of the total composition of a water-soluble compound effective for inhibiting discoloration of said cellulosic fabric under curing conditions and selected from the group consisting of hydrazine, hydrazine salts and derivatives thereof which have only partial substitution of the hydrogens of the H2N-NH2 base and having between 10 and 50 percent by weight of the total composition of a water-soluble inorganic resinous polymeric material produced by reaction of dilute ammonium hydroxide with the reaction product of anhydrous ammonia and a phosphorus compound selected from the group consisting of phosphorus pentoxide and phosphorus oxychloride, said resin being in polymeric form non-reactable with said water-soluble compound and heat curable to a water-insoluble finish in the absence of components which will react with said water-soluble compound before drying and curing temperatures are attained, said resinous component being present as an impregnant in an amount in the range between 15 and 20 percent based upon the dry weight of said fabric and said compound being present as an impregnant in an amount in the range between about 0.05 and 0.5 percent based upon the dry weight of said fabric. 